The number of county students taking International Baccalaureate exams surged last school year, according to data recently released by the school system. But for the first time in at least a decade, Fairfax saw a slight dip in students taking Advanced Placement tests.

While the statistics show the programs heading in different directions, both trends bear the markers of the school system’s continuing effort to boost participation in advanced academic courses, school officials said.

An 8.8 percent increase in students taking IB tests from 2012 to 2013 shows a program coming into its own, according to Chris Powell, the International Baccalaureate specialist for county schools. He linked the stagnation on the AP side, with 0.7 percent fewer test takers, to an expanded slate of honors courses last school year.

“That small drop in kids taking AP courses results in part from the growth of the honors option,” Powell said. “But in the long run honors courses provide more students a gateway to the higher AP and IB levels.”

AP and IB programs offer college-level courses to high school students. End-of-year exams provide the possibility for college credit if students meet scoring benchmarks set by universities. In Fairfax County, eight high schools offer the IB program, while 17 have the AP program.

At the end of the 2012-13 school year, 16,233 students took at least one AP exam. While the number of test takers decreased slightly, students across the county took 35,759 exams, the same total as last year.

The drop in AP test takers ended years of slow but steady growth. Since 2010, the number of county students taking AP exams has increased by 5 percent, and the number of exams taken has increased by 11 percent.

In that same period, the number of students taking IB exams has grown by 20 percent, and the number of exams taken has grown by 26 percent. However, just 3,154 students took 8,137 IB exams in 2013, numbers dwarfed by the behemoth AP program even accounting for difference in population between the AP and IB schools.

Students can be intimidated by the IB program, according to Powell. The program offers the option of pursuing an IB diploma, which requires a more intensive curriculum for high school juniors and seniors, including multiple advanced courses each year.

County schools, though, push an open access model for IB courses, allowing students to choose courses a la carte if they do not want to pursue the IB diploma. That effort, Powell said, is one of the reasons for the program’s continued growth.

“Students are learning that the IB can be a success, whether it’s one course or multiple courses,” Powell said. “We don’t see it as an all-or-nothing opportunity. Students are taking advantage of the open access the schools are providing.”

That push for student choice extends to honors classes. Five new classes were added to the course offerings last year: 11th and 12th grade English, level two world history and geography, Virginia and U.S. history and Virginia and U.S. government.

Students are filling the rosters of these classes, according to Erin Sikes-Thurston, the high school advanced academic programs specialist for the school system. These classes can remove the intimidation of AP and IB classes, Sikes-Thurston said, and can open students to the possibility of more advanced classes.

For Sikes-Thurston, the push for more students across AP, IB and honors programs needs to be a united effort.

“We’re thrilled when kids take an AP or IB test, but we’re just as thrilled when they take an honors class,” Sikes-Thurston said. “Our scores have remained pretty solid, and we think our efforts will lead to further increases in students taking these classes and scoring well on these tests.”

Last year, International Baccalaureate scores in the county saw a small increase and Advanced Placement scores a small decrease. But mean scores across both programs have held relatively steady in the past five years.

On IB exams, 74 percent of county students reached the typical benchmark score for college credit, and on AP exams, 71 percent reached the benchmark score.